Cotton harvesters having two or more harvesting units supported at a forward end of a frame in a side-by-side relation are well-known in the art. Each harvesting unit typically includes rotary picker drums arranged in fore-and-aft relation relative to each other. Each picker drum includes columns of picker spindles radially extending therefrom.
A mounting and support system is provided for connecting the harvesting units to the frame in a manner permitting vertical displacement of the harvesting units between lowered and raised positions. A typical mounting and supporting system includes two elongated tool bar structures extending laterally across the front end of the harvester. One tool bar structure has one or more harvesting units commonly thereon. The remaining harvesting units are commonly mounted on the other tool bar structure. Each tool bar structure is pivotally connected to the frame of the harvester by independently operated lift assemblies.
To facilitate narrow row cotton harvesting (30" row spacing) the picker drums of adjacent harvesting units are preferably nested relative to each other. The nested relationship and close proximity of the harvesting units relative to each other presents interference problems when the harvesting units are independently moved to their raised position.
U.S. Pat. No. 4,722,173 to M. J. Covington et al. provides a lift assembly which advantageously avoids interference problems between adjacent picker drums while permitting their vertical displacement relative to each other. The lift assembly disclosed in the Covington et al. patent vertically moves the harvesting units in substantially parallel relation relative to each other. The ability to move the harvesting units in parallel relation relative to each other furthermore maintains a substantially level attitude for the picker drums of the harvesting units relative to the ground surface over which the harvester moves during operation.
Cotton grows close to the ground on cotton plants. To maximize picking capacity, therefore, each harvesting unit is basically parallel to the ground and typically tilted in a fore-and-aft direction such that a forward end of the harvesting unit is arranged closer to the ground than is the rearward or aft end of the harvesting unit.
When the cotton harvester is driven from one portion or section of a field to another section of the field, the harvesting units are elevated into a raised position. Because the lift assembly is arranged beneath the cab region on the frame of the harvester, the vertical displacement of the harvesting units is limited. Thus, even after the harvesting units are moved into their raised position, the harvesting units remain parallel and close to the ground and define limited ground clearance for the cotton harvester. As will be appreciated, an ability to increase ground clearance reduces the likelihood of damage to the harvesting units as the harvester is transported and enhances harvester mobility.